Genesis 9:6
ESV - 6 Whoever sheds the blood of man, by man shall his blood be shed, for God made man in his own image.
For follow-up discussion and general commentary on the topic. Comments are sorted chronologically.
Human reasoning isn't worth very much for bible study and understanding scripture. Human reasoning calculates everything according to a finite system. (Two plus two equals four. Gravity makes everything cling to the earth with no exceptions).
God's way is not man's way. God doesn't give us all the details of anything!
He tells us the way He wants us to handle a situation, and given the same opportunity in the same situation, He handles it differently. That confuses the finite mind that reasons a law of some kind is broken when that happens, or that there's a flaw in our report. Neither is true!
We're to remember God's character. They are summarized thusly: He is the way, the truth, and the life (John 14:6). These three don't tell us how God operates, they tell us who He is. This is a vague description, in my opinion. It causes the spiritually hungry mind to want to know more.